We investigate identification of causal parameters in case-control and related studies. The odds ratio in the sample is our main estimand of interest and we articulate its relationship with causal parameters under various scenarios. It turns out that the odds ratio is generally a sharp upper...

The study of consumer payment choice at the point of sale involves a classification of payment methods such as cash, credit cards, debit cards, prepaid cards, paper checks, and electronic payments withdrawn from consumers' bank accounts. I describe alternative methods for studying consumer...

The rapid adoption of AI technologies by many organizations has recently raised concerns that AI may eventually replace humans in certain tasks. In fact, when used in collaboration, machines can significantly enhance the complementary strengths of humans. Indeed, because of their immense...